TWI451597B - Optoelectronic device and method for manufacturing the same - Google Patents

Description

Photoelectric element and method of manufacturing same

The present invention relates to a photovoltaic element having a buffer laminate structure formed between a semiconductor and a substrate.

A light-emitting diode is a widely used light source among semiconductor elements. Compared with traditional incandescent bulbs or fluorescent tubes, LEDs have the characteristics of power saving and long service life, so they gradually replace traditional light sources and are used in various fields such as traffic signs, backlight modules, and street lamps. Lighting, medical equipment and other industries.

With the application and development of the light-emitting diode light source, the demand for brightness is getting higher and higher, and how to increase its luminous efficiency to increase its brightness has become an important direction for the industry to work together.

4A is a schematic view showing the structure of a conventional light-emitting element. As shown in FIG. 4A, a conventional light-emitting element 100 includes a transparent substrate 10, a buffer layer 11, a semiconductor laminate 12 on the transparent substrate 10, and at least one. The electrode 14 is disposed on the semiconductor stack 12, wherein the semiconductor stack 12 includes at least a first conductive semiconductor layer 120, an active layer 122, and a second conductive semiconductor layer 124 from bottom to top. The buffer layer 11 includes at least one aperture 111 therein.

However, as shown in FIG. 4B, in the conventional light-emitting element 100, since the aperture 111 in the buffer layer 11 easily causes the light-emitting element 100 to generate a gray surface, the light transmittance is reduced.

A photovoltaic element comprising: a substrate, and a first transition stack on the substrate, wherein the first transition stack comprises at least one first transition layer on the substrate, and the first transition layer has at least one inside The hole structure, and a second transition layer, is an unintentionally doped layer or an undoped layer and is located above the first transition layer.

In order to make the description of the present invention more detailed and complete, please refer to the following description and the diagrams of FIGS. 1A to 1E. As illustrated in FIGS. 1A to 1E, the manufacturing method of the photovoltaic element 100 according to the first embodiment of the present invention is briefly described as follows: as shown in FIGS. 1A to 1B, the substrate 101 having a normal direction N is first. A first transition layer 1021 is grown on the surface 1011, wherein the thickness of the first transition layer 1021 can be between 0.3 μm and 3 μm, or 0.4 μm to 3 μm, or 0.5 μm to 3 μm, or 0.7 μm to 3 μm, or 1 μm to 3 μm. Or 2μm~3μm.

Thereafter, the first transition layer 1021 can be etched by electrochemical etching, anisotropic etching, such as dry etching of inductive coupling plasma (ICP), or using a single oxalic acid, potassium hydroxide, or phosphoric acid sulfuric acid solution. The solution or the mixed solution is subjected to wet etching so that the inside of the first transition layer 1021 includes at least one pore structure, for example, a pore, a void, a pinhole, or at least two pore structures may be connected to each other to form a A porous structure is disclosed in the Taiwan Patent Application No. 099132135, the entire disclosure of which is incorporated herein by reference.

Then, as shown in FIG. 1B, a second transition layer 1022 is grown on the first transition layer 1021, wherein the first transition layer 1021 and the second transition layer 1022 can be collectively referred to as a first transition stack 102a. The second transition layer 1022 may have a growth temperature of 800 to 1200 ° C and a pressure range of 100 to 700 mbar, and the adjustment is matched with the hole size and density of the first transition layer 1021 to perform lateral repair on the first transition layer 1021. Healing, the pores close to the interface between the first transition layer 1021 and the second transition layer 1022 are made smaller, and the second transition layer 1022 continues to grow.

Wherein the plurality of first layer first transition layers 1021 may comprise pore structures of the same or different widths. In one embodiment, the width of the hole structure in each of the plurality of first transition layers 1021 is gradually reduced from near the substrate toward the second transition layer 1022. In this embodiment, the material of the first transition layer stack 102a comprises one or more elements selected from the group consisting of gallium (Ga), aluminum (Al), indium (In), arsenic (As), phosphorus (P), and nitrogen ( N) and 矽 (Si) constitute a group. In an embodiment, the first transition layer 1021 can be an n-type doped layer, and the doping concentration can be 1E15~1E19 cm ^-3 , or 1E16~1E19 cm ^-3 , or 1E17~1E19 cm ^-3 . Or 1E18~1E19 cm ^-3 , or 5x1E18~1E19 cm ^-3 , or 5x1E17~1E19 cm ^-3 , or 5x1E17~1E18 cm ^-3 . In an embodiment, the second transition layer 1022 is an unintentional doped layer or an undoped layer.

In this embodiment, the width of the hole or the mesh hole in the first transition layer 1021 may be between 10 nm and 2000 nm, or 100 nm to 2000 nm, or 300 nm to 2000 nm, or 500 nm to 2000 nm, or 800 nm to 2000 nm, or 1000 nm. 2000 nm, or 1300 nm to 2000 nm, or 1500 nm to 2000 nm, or 1800 nm to 2000 nm. In one embodiment, the hole width closer to the substrate is greater than the hole width closer to the second transition layer.

In another embodiment, the plurality of holes or mesh holes in the first transition layer 1021 may be a regular array structure. The average width W _{x of the} plurality of holes may be between 10 nm and 2000 nm, or 100 nm to 2000 nm, or 300 nm to 2000 nm, or 500 nm to 2000 nm, or 800 nm to 2000 nm, or 1000 nm to 2000 nm, or 1300 nm to 2000 nm, or 1500 nm to 2000 nm. , or 1800nm~2000nm. In an embodiment, the average spacing of the plurality of holes or mesh holes may be between 10 nm and 2000 nm, or 100 nm to 2000 nm, or 300 nm to 2000 nm, or 500 nm to 2000 nm, or 800 nm to 2000 nm, or 1000 nm to 2000 nm. Or 1300nm~2000nm, or 1500nm~2000nm, or 1800nm~2000nm.

The porosity Φ formed by the plurality of holes or mesh groups is defined as the total volume V _V of the holes or mesh holes divided by the total volume V _T ( Wherein the overall volume V _T is the total volume of the first transition layer 1021. In this embodiment, the porosity Φ may be between 5% and 90%, or 10% to 90%, or 20% to 90%, or 30% to 90%, or 40% to 90%, or 50%. 90%, or 60%-90%, or 70%-90%, or 80%-90%. Next, as shown in FIG. 1C, a first semiconductor layer 103, an active layer 104 and a second semiconductor layer 105 are grown on the second transition layer 1022.

Finally, as shown in FIG. 1D, two electrodes 106, 107 are formed on the second semiconductor layer 105 and the substrate 101, respectively, to form a vertical photovoltaic element 100.

In another embodiment, as shown in FIG. 1E, after the active portion 104 and a second semiconductor layer 105 are etched to expose a portion of the first semiconductor layer 103, the first semiconductor layer 103 and the second semiconductor layer 105 are Two electrodes 106, 107 are formed thereon to form a horizontal photovoltaic element 100'. The materials of the electrodes 106 and 107 may be selected from the group consisting of chromium (Cr), titanium (Ti), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), aluminum (Al), or silver (Ag). Metal materials.

1F is a partial scanning electron microscope (SEM) image of a photovoltaic element formed according to the above embodiment of the present invention, comprising a substrate 101, a first transition layer 1021, a second transition layer 1022 and a first semiconductor layer. 103.

The plurality of holes or mesh holes in the first transition layer 1021 are hollow structures, and the plurality of holes or mesh holes have a refractive index, which is suitable as an air lens, when the light travels to the photoelectric element 100 to When a plurality of holes or mesh holes are different, the refractive index difference between the inner and outer materials of a plurality of holes or mesh holes (for example, the refractive index of the semiconductor layer is between 2 and 3, and the refractive index of air is 1) The light will change the direction of travel at a plurality of holes or mesh holes to leave the photovoltaic element, thereby increasing the light extraction efficiency. In addition, a plurality of holes or mesh holes can also serve as a scattering center to change the direction of travel of the photons and reduce total reflection. By increasing the density of the holes, the above effects can be further increased.

The second transition layer 1022 can be an unintentional doped layer or an undoped layer. When growing on the first transition layer 1021, the plurality of holes or meshes are first performed. The repair and healing of the pore group structure, and further epitaxial growth, can avoid the direct growth of the n-type or p-type doped semiconductor layer due to dopant substances, such as (Si) or magnesium (Mg) adsorbed around the hole As a result, the light transmittance is lowered, and the light extraction efficiency of the photovoltaic element is lowered.

As shown in FIGS. 2A-2C, a schematic diagram of a structure of a photovoltaic element according to another embodiment of the present invention is shown. As shown in FIGS. 2A-2C, the first transition layer 102a may also include a plurality of layers of the first transition layer 1021 and A second layer of transition layer 1022. As shown in FIG. 2A, two first transition layers 1021 may be formed on a substrate (not shown) and a second transition layer 1022 may be formed on the first transition layer 1021.

As shown in FIG. 2B, three first transition layers 1021 may be formed on a substrate (not shown) and a second transition layer 1022 may be formed on the first transition layer 1021. As shown in FIG. 2C, the n-layer first transition layer 1021, n ≧ 4, may also be included depending on the actual design of the component to achieve a better optical effect or stress reduction effect. In this embodiment, any of the first transition layers 1021 includes at least one pore structure, which may be a pore, void, or a pinhole, or at least two pore structures may be connected to each other to form a mesh. The porous structure, the forming method, material, size and other characteristics are the same as those in the above embodiment, and will not be described herein.

As shown in FIGS. 3A to 3C, there is shown a schematic structural view of a photovoltaic element according to another embodiment of the present invention: as shown in FIG. 3A, a photovoltaic element 200 according to another embodiment of the present invention, in this embodiment, A second transition stack 102b may also be included over a transition stack 102a. In an embodiment, the first transition stack 102a, as in the above embodiment, may include at least one first transition layer (not shown) and a second transition layer (not shown), and the second transition stack 102b, At least one first transition layer (not shown) and one second transition layer (not shown) may be included. In another embodiment, as illustrated in the above embodiments, the first transition stack 102a and the second transition stack 102b may also respectively include a plurality of first transition layers (not shown), and each first transition layer (not shown) includes at least one pore structure, which may be a pore, void, or a pinhole, or at least two pore structures may be connected to each other to form a porous structure. The formation method, material, size and other characteristics are the same as those of the above embodiment, and will not be described again.

As shown in FIG. 3B, a photovoltaic element 300 according to another embodiment of the present invention may further include a second transition layer 102b and a third transition layer on the first transition layer 102a. 102c, wherein the first transition layer 102a, as in the above embodiment, may include at least one first transition layer (not shown) and a second transition layer (not shown), and the second transition stack 102b may include at least a first transition layer (not shown) and a second transition layer (not shown), and the third transition stack 102c may include at least one first transition layer (not shown) and a second transition layer ( The figure is not shown). In an embodiment, as illustrated in the above embodiments, the first transition stack 102a, the second transition stack 102b, and the third transition stack 102c may also include a plurality of first transition layers (not shown), and Each of the first transition layers (not shown) includes at least one pore structure, which may be a pore, void, or a pinhole, or at least two pore structures may be connected to each other to form a mesh-like pore structure. (porous structure), the formation method, material, size and other characteristics are the same as those of the above embodiment, and will not be described herein.

As shown in FIG. 3C, a photovoltaic element 400 according to another embodiment of the present invention may further include a second transition layer 102b and a third transition layer on the first transition layer 102a. 102c ... to an n-th layer transition stack, wherein n ≧ 4, wherein each transition stack may comprise at least one first transition layer (not shown) and a second transition layer (not shown) ). In an embodiment, as illustrated in the above embodiments, each transition stack may also include a plurality of first transition layers (not shown), and each of the first transition layers (not shown) includes at least one The pore structure may be a pore, void, or a pinhole, or at least two pore structures may be connected to each other to form a porous structure, a method, a material, a size, and other characteristics. The same as the above embodiment, and details are not described herein again.

Specifically, the photovoltaic elements 100, 200, 300, and 400 include a light emitting diode (LED), a photodiode, a photoresistor, a laser, and an infrared emitter. At least one of an organic light-emitting diode and a solar cell. The substrate 101 is a growth and/or carrier foundation. The candidate material may comprise a conductive substrate or a non-conductive substrate, a light transmissive substrate or an opaque substrate. One of the conductive substrate materials may be germanium (Ge), gallium arsenide (GaAs), indium phosphate (InP), tantalum carbide (SiC), germanium (Si), lithium aluminate (LiAlO ₂ ), zinc oxide (ZnO). ), gallium nitride (GaN), aluminum nitride (AlN), metal. One of the transparent substrate materials may be sapphire, lithium aluminate (LiAlO ₂ ), zinc oxide (ZnO), gallium nitride (GaN), aluminum nitride (AlN), metal, glass, diamond, CVD diamond, And Diamond-Like Carbon (DLC), spinel (MgAl ₂ O ₄ ), alumina (Al ₂ O ₃ ), yttrium oxide (SiO _X ), and lithium gallate (LiGaO ₂ ).

The first semiconductor layer 103 and the second semiconductor layer 105 are different in electrical conductivity, polarity, or dopant from at least two portions, or are used to provide a single or multiple layers of semiconductor materials for electrons and holes, respectively (" "Multilayer" means two or more layers, the same applies hereinafter.) The electrical selection may be a combination of at least any two of p-type, n-type, and i-type. The active layer 104 is located between the first semiconductor layer 103 and the second semiconductor layer 105, and is a region where electrical energy and light energy may be converted or induced to be converted. Those who convert or induce light energy are such as light-emitting diodes, liquid crystal displays, and organic light-emitting diodes; those that convert or induce light energy are such as solar cells and photodiodes. The first semiconductor layer 103, the active layer 104, and the second semiconductor layer 105 have a material containing one or more elements selected from the group consisting of gallium (Ga), aluminum (Al), indium (In), arsenic (As), and phosphorus (P). ), a group of nitrogen (N) and bismuth (Si).

The photovoltaic element 100, 200, 300, 400 according to another embodiment of the present invention is a light-emitting diode whose light-emitting spectrum can be adjusted by changing the physical or chemical elements of the semiconductor single layer or layers. Commonly used materials are such as aluminum gallium indium phosphide (AlGaInP) series, aluminum gallium indium nitride (AlGaInN) series, zinc oxide (ZnO) series and the like. The structure of the active layer 104 is, for example, a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), or a multi-layer quantum well (multi- Quantμm well; MQW). Furthermore, adjusting the logarithm of the quantum well can also change the wavelength of the illumination.

In one embodiment of the present invention, the first semiconductor layer 103 and the first transition layer 102a or the first transition layer 102a and the substrate 101 may optionally include a buffer layer (not shown). The buffer layer is interposed between the two material systems to "transition" the material system of the substrate to the material system of the semiconductor system. For the structure of the light-emitting diode, on the one hand, the buffer layer is used to reduce the material layer of the lattice mismatch between the two materials. In another aspect, the buffer layer may also be a single layer, a plurality of layers or a structure for combining two materials or two separate structures, such as organic materials, inorganic materials, metals, and semiconductors; The selected structure is: reflective layer, thermally conductive layer, conductive layer, ohmic contact layer, anti-deformation layer, stress release layer, stress adjustment layer, bonding layer, wavelength Conversion layer, mechanical fixing structure, etc. In an embodiment, the material of the buffer layer may be AlN, GaN, and the forming method may be sputtering or Atomic Layer Deposition (ALD).

A contact layer (not shown) is more selectively formed on the second semiconductor layer 105. The contact layer is disposed on a side of the second semiconductor layer 105 away from the active layer 104. In particular, the contact layer can be an optical layer, an electrical layer, or a combination of both. The optical layer can change the electromagnetic radiation or light from or into the active layer 104. As used herein, "change" means changing at least one optical property of electromagnetic radiation or light, including but not limited to frequency, wavelength, intensity, flux, efficiency, color temperature, rendering index, light field. (light field), and angle of view. The electrical layer system may change or change the value, density, distribution of at least one of voltage, resistance, current, and capacitance between opposite sides of any one of the contact layers. The constituent material of the contact layer comprises an oxide, a conductive oxide, a transparent oxide, an oxide having a transmittance of 50% or more, a metal, a relatively light-transmissive metal, a metal having a transmittance of 50% or more, an organic substance, At least one of an inorganic substance, a phosphor, a phosphor, a ceramic, a semiconductor, a doped semiconductor, and an undoped semiconductor. In some applications, the material of the contact layer is at least one of indium tin oxide, cadmium tin oxide, antimony tin oxide, indium zinc oxide, zinc aluminum oxide, and zinc tin oxide. In the case of a relatively light-transmissive metal, the thickness is about 0.005 μm to 0.6 μm.

The above figures and descriptions are only corresponding to specific embodiments, however, the elements, embodiments, design criteria, and technical principles described or disclosed in the various embodiments are inconsistent, contradictory, or difficult to implement together. In addition, we may use any reference, exchange, collocation, coordination, or merger as required.

Although the invention has been described above, it is not intended to limit the scope of the invention, the order of implementation, or the materials and process methods used. Various modifications and variations of the present invention are possible without departing from the spirit and scope of the invention.

101. . . Substrate

102a. . . First transition stack

102b. . . Second transition stack

102c. . . Third transition stack

1021. . . First transition layer

1022. . . Second transition layer

103. . . First semiconductor layer

104. . . Active layer

105. . . Second semiconductor layer

106, 107. . . electrode

1A to 1E are schematic views showing a process of a photovoltaic element according to an embodiment of the present invention;

1F is a partial scanning electron microscope (SEM) image of a photovoltaic element formed according to an embodiment of the present invention;

2A to 2C are diagrams showing the structure of a photovoltaic element according to another embodiment of the present invention;

3A to 3C are diagrams showing the structure of a photovoltaic element according to another embodiment of the present invention;

Figure 4A is a schematic view showing the structure of a conventional light-emitting element;

Fig. 4B is a top view showing the structure of a conventional light-emitting element.

101. . . Substrate

102a. . . First transition stack

103. . . First semiconductor layer

104. . . Active layer

105. . . Second semiconductor layer

106, 107. . . electrode

Claims (18)

A photovoltaic element comprising: a substrate; and a first transition stack over the substrate, wherein the first transition stack comprises at least a first transition layer over the substrate, and the first transition layer The interior has at least one hole structure, and a second transition layer is an unintentionally doped layer or an undoped layer and is located above the first transition layer. The photovoltaic device according to claim 1, wherein the hole structure has a width, wherein the width is a maximum dimension of the hole structure in a direction parallel to the surface, and the width is between 10 nm and 2000 nm. The photovoltaic element of claim 1, wherein the photovoltaic element comprises a plurality of the hole structures, the hole structures may be coupled to each other to form one or a plurality of mesh holes; or the holes are in a regular array, and The pore structures have an average spacing of 10 nm to 2000 nm and a porosity of 5% to 90%. The photovoltaic device of claim 1, further comprising a first semiconductor layer, an active layer and a second semiconductor layer formed on the transition stack, wherein the transition stack, the first semiconductor layer, the active The material of the layer and the second semiconductor layer comprises one or more elements selected from the group consisting of gallium (Ga), aluminum (Al), indium (In), arsenic (As), phosphorus (P), nitrogen (N), and antimony ( Si) is a group. The photovoltaic element of claim 2, wherein the width of the hole structure closer to the substrate is greater than the width of the hole structure closer to the second transition layer. The photovoltaic element according to claim 2, wherein the transition layer comprises a plurality of first transition layers, and the plurality of first transition layers comprise pore structures of different widths, and the plurality of layers of the first transition layer The width of the hole structure tapers from near the substrate toward the second transition layer. The photovoltaic element of claim 1, further comprising a second transition stack formed on the first transition stack, wherein the second transition stack comprises at least one first transition layer, the first transition stack Above the layer, the first transition layer has at least one hole structure inside, and a second transition layer is an unintentionally doped layer or an undoped layer, and is located above the first transition layer. The photovoltaic device of claim 1, wherein the first transition layer is an n-type doped layer, and the doping concentration may be between 1E15 and 1E19 cm ^-3 . A method of fabricating a photovoltaic element, comprising the steps of: providing a substrate; forming a first transition layer over the substrate; forming at least one hole structure in the first transition layer; and forming a second transition layer Above the first transition layer, wherein the second transition layer is an unintentionally doped layer or an undoped layer. The method of claim 9, wherein the step of forming the void structure in the first transition layer comprises electrochemical etching, anisotropic dry etching, or anisotropic wet etching. The method of claim 9, wherein the hole structure has a width, wherein the width is a maximum dimension of the hole structure in a direction parallel to the surface, and the width is between 10 nm and 2000 nm. The method of claim 9, wherein the photovoltaic element comprises a plurality of the hole structures, the hole structures may be coupled to each other to form one or a plurality of mesh hole groups; or the hole structures are in a regular array, and the hole structure The pore structures have an average spacing of 10 nm to 2000 nm and a porosity of 5% to 90%. The method of claim 9, further comprising forming a first semiconductor layer, an active layer and a second semiconductor layer over the transition stack, wherein the transition stack, the first semiconductor layer, the active layer And the material of the second semiconductor layer comprising one or more elements selected from the group consisting of gallium (Ga), aluminum (Al), indium (In), arsenic (As), phosphorus (P), nitrogen (N), and antimony (Si) ) the group formed. The method of claim 11, wherein the width of the hole structure closer to the substrate is greater than the width of the hole structure closer to the second transition layer. The method of claim 11, wherein the transition stack comprises a plurality of first transition layers, and the plurality of first transition layers comprise pore structures of different widths, and the holes in the layers of the first transition layer of the plurality of layers The width of the structure tapers from near the substrate toward the second transition layer. The method of claim 9, wherein the first transition stack further comprises a first transition layer forming a plurality of layers between the substrate and the second transition layer. The method of claim 9, further comprising forming a second transition stack over the first transition stack, wherein the second transition stack comprises at least one first transition layer over the first transition stack Above, the first transition layer has at least one hole structure inside, and a second transition layer is an unintentionally doped layer or an undoped layer, and is located above the first transition layer. The method of claim 9, wherein the first transition layer is an n-type doped layer, and the doping concentration may be between 1E15 and 1E19 cm ^-3 .